Any suggestions how to rejuvenate some "sparkling" to this trim piece?

 

I was going to suggest a trip down to Tacoma for a visit with the folks at Griot's Garage if the hour and half trip would be worth it. (a great place for lunch just up the street from them is Dirty Oscar's Annex). Or, they have helpful videos on line on how to use their products.

 

Try a black trim treatment of some kind, or paint them.

 

Paint is absolutely not an option. Neither removing the upper and lower grille assembly from the car for detailing.

The pattern of the JCW upper and lower grille is some kind of a 3D thicker pattern different from the S simple mesh thin grille.

 

Black shoe shine did an outstanding job. Time consuming but worth it.

 

After you posted this I started using my quarentime to clean up the black trim on my R53. Went the Penetrol route, pretty happy with the results, we'll see how it holds up in the long run.

 

I use a product called Simple Solution it comes in black or grey. You should use cloves when applying and dont let it set on paint to long because some have said it stained it, I have never had that problem. It will take some time to get in all the mesh areas and corners. Let it set and wipe it off.i just did it to my lower section that was very dull. Works great on all of the outside Mini black trim. Ruff surfaces like wheel arches will not be a glossy shine "that's what I like" but very smooth plastic surfaces will have a slight shine. Just wipe those down extra good.

 

Once a year I take a bit of Black Wow and apply it using a long bristled detailing brush so I can get it down into all the diamonds. It seems to last me well for a year or so.